Optimization Design of Muffler External Geometry Integrated with Motorcycle Exhaust Thermoelectric Generator System

The thermoelectric generator system (TGS) is a potential technology for recovering waste heat from internal combustion engines but can increase pressure loss of the exhaust system. In this work, four computational fluid dynamics simulation series were conducted to determine the optimal muffler configuration which produces minimum pressure drop. Firstly, the rounded radius α between the inlet pipe and the muffler front wall was varied. Secondly, two options are considered for either rounded radius β or slope chamfer angle θ between the front wall, top wall, and bottom wall of the muffler to select the optimal value. Thirdly, the rounded radius φ between the muffler back wall and the outlet pipe was varied. Finally, the slope chamfer angle γ between the muffler’s back wall, top wall, and bottom wall was optimized. The results indicate that rounding and chamfering at the muffler’s inlet and outlet compartments reduce pressure losses by mitigating the effect of flow expansions or contractions thanks to diminishing flow separation, swirling, and local velocity. The optimal parameters are α = 12 mm, θ = 60°, φ = 12 mm, and γ = 40°. The new muffler’s pressure drop was reduced to 53% of the original. The optimal muffler reduces pressure loss while ensuring the TGS’s heat transfer and thermal uniformity. This work provides a method to reduce pressure loss of TGS by optimizing muffler geometry. It also decreases muffler size and weight, enhancing their suitability for motorcycles.